Control apparatus



Jan. 23, 1962 L. F. WARNQCK, JR

CONTROL APPARATUS Filed Feb. 21, 1961.

FIG. i

m U L F S U 0 C E V 2 5 0 LLATORY WER SUPPLY FIG. 3

INVENTOR.

LYLE E WARNOCK JR.

ATTORNEY Bflld til 9 Patented Jan. 23, llfi2 3,018,141 @UNTRGL APPARATU Lyle F. Warnoclr, .lrn, Grand Rapids, Mich, assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Filed Feb. 21, 1961, Ser. No. 90,681 6 Claims. (Cl. 308-9) This invention is concerned with a low friction support and has special although not exclusive application to the field of inertial instruments. In one embodiment, the present invention provides a hydrodynamic gimbal support for a floated inertial instrument. In this embodiment the invention provides means for rotatably connecting a gimbal member to a housing member for relative rotation thcrebetween about an axis, the connecting means including a pair of axially spaced bearing assemblies. Each of the bearing assemblies includes a chamber in one of the members and pivot means on the other of the members, at least a portion of the pivot means being positioned within the chamber. A plurality of vanes are provided on one of the members extending radially in the chamber toward the pivot means defining therebetween restrictive gap means. A second plurality of vane means are provided on the portion of the pivot means within the chamber and the second vane means extend radially toward the other of the members defining therebetween additional restrictive gap means. The invention also provides means for rotationally oscillating the pivot means relative to the other of the members so that the first plurality of vanes are rotationally oscillated relative to the second plurality of vanes. The invention provides fluid means to be disposed at least within the chamber. Accordingly the vane means coact with the fluid means to pump the fluid means through the restrictive gap means. With this arrangement the gimbal member is supported for relative rotation with respect to the housing member about an axis. Any tendency of the gimbal axis to be displaced away from the rotational axis is opposed by fluid forces due to the fact that such a tendency would tend to decrease some of the restrictive gaps while at the same time other restrictive gaps would increase in size. The fluid pressures would tend to increase in the zones adjacent to the decreased restrictive gaps while the pressures adjacent the increased restrictive gaps would decrease and accordingly a resultant force would be applied to the gimbal member tending to shift it toward its centered position. Another facet of the invention is to provide means for controlling the oscillating means so that the oscillating means of one of the assemblies is rotated about its axis 180 out of phase with respect to the oscillating means of the other assembly.

It is an object of this invention therefore to provide an improved control apparatus.

Another object of the invention is to provide an irnproved rotational support for a sensitive instrument.

A further object of the invention is to provide an improved gimbal support for a floated inertial instrument.

These and other objects and advantages of the invention will become more apparent from a reading of the following detailed description and appended claims in connection with the drawings in which:

FEGURE l is a cross-sectional view of a portion of a floated gyroscope embodying the teaching of the invention;

FIGURE 2 is a transverse cross-sectional view of the apparatus depicted in FIGURE 1 as viewed along section lines 2-2-; and

FIGURE 3 is a schematic representation of a sensitive instrument provided with a pair of axially spaced bearing assemblies embodying the teaching of the present invention.

Referring first to FIGURE 3 the reference numeral 10 generally designates a control apparatus of the floated gyro type and comprises a support or base or housing member 11 and a gimbal member or second member 12 adapted to be rotatably supported with respect to the base or housing member 11 about a rotational axis 13 which in the case of a floated integrating gyroscope also would be identified as the output axis. The rotational support for the gimbal with respect to the housing 11 is provided by a pair of axially spaced bearing assemblies generally designated by the reference numerals 1d and 15 and shown in greater detail in FIGURES 1 and 2. Associated with the bearing assemblies 14 and 15 are oscillatory motor means 16 and 17 respectively which in turn receive energization from a suitable source such as an oscillatory power supply 211 and 2.1 respectively.

A gyroscope rotor element 2.2 is provided within the gimbal 12 for rotation about a spin reference axis 23 which generally is at right angles with respect to the output axis 13. Generally fluid means would be provided surrounding the gimbal 12 and being associated with the bearing assemblies 14 and 15. This will be identified in FIGURE 1 but is not disclosed in FIGURE 3 due to the schematic nature of FIGURE 3.

The bearing assemblies 14 and 15 structure-wise are preferably identical to one another and accordingly in FIGURE 1 only a detailed showing of the hearing as sembly 15 is depicted. In FIGURE 1 the housing member 11 is shown as a generally hollow cylindrical enclosure having a main inner bore Ell. The housing 11 is provided with an end plate or cover having a gen erally circular configuration and is attached by suitable means not shown to the housing. The gimbal member 12 generally has a cylindrical exterior configuration and the outer diameter 32 thereof is slightly less than the diameter of the bore 38 of the housing 11 defining therebetween a damping gap 33. A hollow chamber 34 is provided within the gimbal 12;. Positioned therein is a gyro motor means including a rotor element 35 supported by suitable means for rotation about a spin reference axis as. It will be understood that the present invention may be applied to other inertial instruments such as accelerometers as well as to other sensitive instruments and control apparatus.

The bearing assembly 15 comprises in part chamber means in one of the members (either the gimbal member or the housing member). in the specific embodiment depicted, the chamber means is provided in a suitable extension of the gimbal 12 and is generally identified by the reference numeral The chamber means 413 has a principal outer diameter identified by the reference numeral 41 and generally is centrally positioned and axially extending with respect to the gimbal 12'. The chamber 49 is further defined by an end plate 4 2 which is attached to the end of the gimbal 12 by suitable means not shown and which further has a central aperture 13 to permit the passage therethrough of a shaft member The shaft member 54 is supported for rotation with respect to the housing 11 by a suitable means, the form depicted being a pair of spaced conventional anti-friction bearings 46 and 47. The inner races of the bearings 46 and 47 are suitably connected to the shaft 44. The outer race of bearing 46 is secured within a central aperture 43 of a mounting plate 49 which is in turn secured at its outer periphery by suitable means to the housing 11. The outer race of the bearing means 47 is positioned in a central hub 51 located on the inner surface of the cover member 31 of the housing 11.

As indicated the shaft 44 passes through the aperture 43 in the gimbal plate 42, a gap being defined therebetween so as to permit the flow of fluid therethrough. Generally the housing 11 would be filled with a suitable fluid such as a viscous damping fluid 52 the fluid 52 surrounding the gimbal assembly 12 and filling all void spaces including; the damping gap 33 and also filling the chamber 41} of the bearing assembly 15.

The shaft 44 is one element of a pivot means which is generally identified by the reference numeral 66 and a large portion of which is positioned within the cl1amher 40.

First vane means are provided on one of the members. In the embodiment depicted, the first vane means takes the form of a plurality of individual vanes 61 which are part of the overall gimbal assembly 12 and generally extend from the periphery or outer diameter 1 of the chamber 413 radially inward toward the output axis 13 and also toward the pivot means 69. More specifically the pivot means 66 within the chamber 40 has a generally cylindrical portion having a periphery 62. In FIGURE 2 four vanes 61 are depicted and are equally spaced about the output axis 13. The vanes 61 extend toward the periphery 62 of the pivot means 69 defining therebetween restrictive gap means 63.

Second vane means are provided and in this embodiment take the form of four equally spaced vane elements 6'5 extending radially outward from the pivot means 6% and forming a part thereof and in turn defining restrictive gap 66 between the outer faces thereof and the periphery 41 of the chamber 40. In the position shown in FIGURE 2, the vanes 65 are interpositioned between the vanes 61.

Suitable means are provided for oscillating the two vaned elements of the supporting means. More specifically in the embodiment depicted, suitable motor means are provided for producing relative oscillatory rotation of the pivot means 6%} with respect to the gimbal member 12 with its associated vanes 61. Various arrangements may be used for the motor means and the electric motor means depicted is only one of various arrangements encompassed by the scope of the invention. The electric motor means depicted is a conventional rotary induction motor such as a hysteresis type or squirrel cage type and which is generally identified by reference numeral 70. It will be understood that motor 70 corresponds with the motor means 17 depicted in FIGURE 3. The motor 70 includes a suitable stator element 71 secured at its outer periphery by suitable means not shown to the housing 11 and having associated therewith suitable winding means 72. The stator element 71 upon energization thereof is adapted to produce an oscillatory rotative magnetic flux which is in turn adapted to coact with a suitable rotor means generally identified by the reference numeral 73 and which in turn is secured by suitable means to the shaft 44. As indicated in connection with FIGURE 3, suitable energization means for the motor means is provided and is generally depicted in FIGURE 3 by the oscillatory power supply 21.

The main purpose of the oscillatory motor means 70 is to cause relative oscillatory rotation of the pivot means tl with respect to the gimbal 12 so that the vanes 65 on the pivot means at oscillate rotationally small angular amounts with respect to the vanes 61 on the gimbal 12. In operation the fluid means 52 will fill all of the voids within the chamber 40 and accordingly will coact with the vane means 61 and 65 upon relative oscillation therebetween. More specifically the fluid means 52 will be pumped through the restrictive gap means 63 and 66, the direction of flow first being in one sense through the gaps and then upon reversal of direction of the vane means will flow in the opposite sense. The frequency of oscillation of the vane means as well as the clearances between the pivot means 60 and the gimbal means 12 are not critical but would be selected as a function of several factors including the type of fluid 52 being used as well as the desired amount of support needed to rotationally support the gimbal 1.2 for relative rotation about axis 13 with respect to housing 11. Generally in FIGURE 2 the clearance between the pivot means 66 and the gimbal 12 has been greatly exaggerated to permit illustration. In one application, a nominal clearance of .002 inch for the restrictive gaps 63 and 66 was found satisfactory. In FIGURE 1 an appreciable axial clearance has been shown between the pivot means 6%} and the gimbal I2 and its associated end cover 42. Generally these gaps would be minimized so as to avoid lessening the effect of the fluid 52 being pumped through the restrictive gaps 63 and 66.

In operation the depicted bearing arrangement rotationally supports the gimbal 12 for relative rotation with respect to the housing 11. Generally in a floated instrument the density of the viscous damping fluid is selected and the gimbal is designed so that the average gimbal density substantially matches the density of the fluid. However, it is almost impossible to exactly match the density especially over a range of temperatures and accordingly the gimbal may be slightly overfloated or underfloated and this in turn will tend to radially shift the gimbal with respect to the housing 11. t follows therefore that this would tend to decrease some of the gaps 63 and 65 while at the same time increasing some of the gaps 63 and 66. Assume that the gimbal due to being overfloated tends to move upwardly in FIGURES 1 and 2 with respect to the housing 11. This would tend to decrease the restrictive gaps at the top while increasing the gaps at the bottom. For example in FIGURE 2 one of the gaps 66 has been identified with the additional designator A while the bottom restrictive gap has been identified by the additional designator B. For the example given restrictive gap A would tend to decrease while restrictive gap B would tend to increase. Due to the rotational oscillation between the pivot means 60 and the gimbal 12 and due to the decreased gap A and increased gap B, there will be a pressure differential tending to return the gimbal radially toward its original position. This is because the reduced gap A produces a higher pressure in this zone as compared to a lowered pressure in the zone adjacent gap B. The same thing happens with respect to the gaps 63 defined between the vanes 61 and the periphery 62 of the central portion of the pivot means 65 In other words a centering force is also developed due to the pumping of the fluid through the restrictive gap 63 and the sense of the centering force is additive with the sense of the centering force resulting from fluid flowing through the restrictive gap 66.

In some embodiments of the invention, it will be found necessary to oscillate one of the bearing assemblies out of phase with respect to the other bearing assembly. With this arrangement which could be used on a floated instrument such as that depicted in FIGURE 1, the tendency for a rotative torque to be applied to the gimbal assembly by one of the bearing assemblies will be offset by an equal and opposite torque produced by the other bearing assembly. In this manner there will be no resultant torque acting on the gimbal tending to rotate it about the output axis. It will be understood that in some applications of the invention, only a single bearing assembly would be needed.

While I have shown and described a specific embodiment of this invention, further modifications and improvements will occur to those skilled in the art. I desire it to be understood, therefore, that this invention is not limited to the particular form shown and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of this invention.

What is claimed is:

1. In a floated inertial instrument: a housing member; a gimbal member positioned within said housing member; fluid means in said housing member and surrounding said gimbal member, said fluid means having a density substantially equal to the density of said gimbal memher; and means rotatably connecting said gimbal member to said housing member for relative rotation therewith about an axis comprising a pair of axially spaced bearing assemblies each including chamber means in one of said members, pivot means on the other of said members and having at least a portion thereof positioned in said chamber means, first vane means on said one of said members extending radially in said chamber toward said pivot means defining therebetween restrictive gap means, second vane means on said portion of said pivot means extending radially toward said one of said members defining therebetween restrictive gap means, and means for rotationally oscillating said pivot means relative to said one of said members so that said first vane means is rotationally oscillated relative to said second vane means, said vane means coacting with said fluid means to pump said fluid means through said restrictive gap means upon relative rotation between said first and second vane means.

2. In control apparatus: a first member; a second member; means rotatably connecting said first member to said second member for relative rotation therewith about an axis comprising a pair of axially spaced bearing assemblies each including chamber means in one of said members, pivot means on the other of said members and having at least a portion thereof positioned in said chamber means, first vane means on said one of said members extending radially in said chamber means toward said pivot means defining therebetween restrictive gap means, second vane means on said portion of said pivot means extending radially toward said one of said members defining therebetween restrictive gap means, fluid means in said chamber means, and means for rotationally oscillating said pivot means relative to said one of said members so that said first vane means is oscillated relative to said second vane means, said vane means coacting with said fluid means to pump said fluid means through said restrictive gap means upon relative rotation between said first and second vane means; and means controlling said oscillating means so that the oscillating means of one of said assemblies is rotated about said axis 180 out of phase with respect to the oscillating means of the other of said assemblies.

3. In control apparatus: a first member; a second member; and means rotatably connecting said first member to said second member for relative rotation therewith about an axis comprising chamber means in one of said members, pivot means on the other of said members and having at least a portion thereof positioned in said chamber means, first vane means on said one of said members extending radially in said chamber means toward said pivot means defining therebetween restrictive gap means, second vane means on said portion of said pivot means extending radially toward said one of said members defining therebetween restrictive gap means, fluid means in said chamber means, and means for oscillating said pivot means relative to said one of said members so that said first vane means is oscillated relative to said second vane means, said vane means coacting with said fluid means to pump said fluid means through said restrictive gap means upon relative movement between said first and second vane means.

4. In a sensitive instrument: a first member; a second member; and means rotatably connecting said first member to said second member for relative rotation therewith about an axis comprising chamber means in one of said members, pivot mean on the other of said members and having at least a portion thereof positioned in said chamber means, first vane means on said one of said members extending radially in said chamber means toward said pivot means defining therebetween restrictive gap means, second vane means on said portion of said pivot means extending radially toward said one of said members defining therebetween restrictive gap means, fluid means, and means for rotationally oscillating said pivot means relative to said one of said members so that said first vane means is rotationally oscillated relative to said second vane means, said vane means coacting with said fluid means to pump said fluid means through said restrictive gap means upon relative rotation between said first and second vane means.

5. In a sensitive instrument: a first member; a second member; and means rotatably connecting said first member to said second member for relative rotation therewith about an axis comprising chamber means in one of said members, pivot means on the other of said members and having at least a portion thereof positioned in said chamber means, first vane means on said one of said members extending radially in said chamber means toward said pivot means, second vane means on said portion of said pivot means extending radially toward said one of said members, restrictive gap means, fluid means in said chamber means and means for oscillating said pivot means relative to said one of said members so that said first vane means is oscillated relative to said second vane means, said vane means coacting with said fluid means to pump said fluid means through said restrictive gap means upon relative movement between said first and second vane means.

6. In a sensitive instrument: a first member; a second member; and means movably connecting said first member to said second member for relative movement therebetween relative to an axis and comprising chamber means in one of said members, pivot means on the other of said members and having at least a portion thereof positioned in said chamber means, vane means on one of said members extending in said chamber means toward the other of said members, restrictive gap means, fluid means in said chamber means, means connected to said members for oscillating said vane means on one of said members relative to the other of said members, said oscillating vane means coacting with said fluid means to pump said fluid means through said restrictive gap means to provide support of one of said members relative to the other of said members.

References Cited in the file of this patent UNITED STATES PATENTS 2,900,823 White Aug. 25, 1959 

